I completely agree! Today, as far as I know, only Facebook Messenger comes even close to supporting it.
Specifically, Messenger can show you an "online now" tab, indicating who is currently at least using Messenger or Facebook, and can even show you "Active now" versus "Active 30m ago".
Specifically, Messenger can show you an "online now" tab, indicating who is currently at least using Messenger or Facebook, and can even show you "Active now" versus "Active 30m ago".